Although broad agreement exists that genetic factors are important contributors to individual differences in pain sensitivity and risk for developing painful clinical conditions, the field of pain genetics is still in its infancy. This article reviews recent human studies of the genetics of acute and chronic pain, which implicate polymorphisms in genes coding for catechol-O-methyltransferase activity and micro-opioid receptors, among a number of others, as influential in explaining variability among the pain responses of individuals. Growing interest in pain genetics and accelerating methodologic advances in the field will almost certainly alter our understanding of which genes contribute to nociception and how dynamic interactions between multiple genes and environmental events shape the human experience of pain.